An electric component mounted on an automobile or the like is connected to another electric component or a power source device through a wire harness which is formed by binding insulated wires thus forming an electric circuit. In this case, the wire harness, the electric component and the power source device are connected to each other by making connectors mounted on these parts respectively engage with each other by a male-female fitting engagement. A crimp-connection structural body where insulated wires and a crimp terminal are connected to each other is mounted on the connector.
The crimp terminal of the crimp-connection structural body is roughly classified into two types depending on a configuration of a crimp section which pressure-bonds the insulated wires. This will be described in more detail. The crimp terminal is classified into an open-barrel-type crimp terminal where a crimp section having one open end is formed into an approximately U shape in vertical cross section and a closed-barrel-type crimp terminal where a crimp section is formed into an approximately cylindrical shape.
In these two types of crimp terminals, the open-barrel-type crimp terminal is configured such that, for example, a portion of the crimp section on which a conductor exposed from an insulating cover is placed and which projects from the insulated wires is folded inward, and a distal end of the folded portion is inserted into the conductor thus crimp the conductor. With such a configuration, in the crimp-connection structural body which uses the open-barrel-type crimp terminal, conductivity is ensured by increasing a contact area between the conductor of the insulated wires and the crimp section of the crimp terminal.
On the other hand, with respect to the closed-barrel-type crimp terminal, for example, as in the case of a conductor connecting method described in Patent Document 1, a conductor of insulated wires is inserted into a connecting pipe portion of a crimp terminal which mounts a compression-use collar on an outer peripheral surface thereof and, thereafter, the compression-use collar is caulked into a hexagonal cross-sectional shape by a pair of dies thus crimp the conductor. With such a configuration, in the crimp-connection structural body which uses the closed-barrel-type crimp section, it is considered that the conductor can be pressure-bonded by the connecting pipe portion having a narrowed diameter while maintaining the shape of an inner peripheral surface which is a circular cross-sectional shape.
Further, in another crimp-connection structural body which uses a closed-barrel-type crimp terminal 50, as shown in FIG. 15 which shows a cross section in a width direction of a conductor crimp section 51 of the conventional crimp-connection structural body, the conductor crimp section 51 having an approximately cylindrical shape is plastically deformed in a diameter narrowing direction, and a crimp recessed portion 52 having an arbitrary shape is formed on the conductor crimp section 51 toward the center in a radial direction thus connecting the conductor crimp section 51 and a conductor 60 to each other by crimp.
Further, in the conductor crimp section 51 shown in FIG. 15, due to the formation of the crimp recessed portion 52 in addition to plastic deformation in the diameter narrowing direction, projecting portions 53 which project outward in the radial direction are formed adjacently to the crimp recessed portion 52. In this specification, the width-direction cross section indicates a cross section in the width direction Y approximately orthogonal to a long length direction of the conductor crimp section 51.
In another such crimp-connection structural body, the conductor 60 is strongly pressure-bonded by the crimp recessed portion 52, and a contact length of a contact portion between an inner peripheral surface of the conductor crimp section 51 and an outer peripheral surface of the conductor 60 is elongated in cross section in the width direction Y thus ensuring conductivity.
On the other hand, in another such crimp-connection structural body, at the time of crimp the conductor crimp section 51 and the conductor 60 to each other, there may be a case where assembling property is lowered or a case where irregularity occurs in a crimp shape depending on the shape of an inner surface of a crimp die.
For example, in the case where crimp of the conductor 60 and separation of a carrier and the crimp terminals 50 by cutting are performed by vertically caulking a plurality of crimp terminals 50 connected to an approximately strip-shaped carrier using one set of crimp dies, depending on a depth of an inner surface of the die positioned on a lower side, it is necessary to prepare a step of placing the conductor crimp section 51 of the crimp terminal 50. Alternatively, for example, in the case where the crimp terminals 50 are pressure-bonded by one set of crimp dies, there is a possibility that projecting portions 53 are not plastically deformed in conformity with the shape of an inner surface of the crimp die and hence, irregularity occurs in shape of the projecting portions 53.
Further, an entire width W1 which is a length in an approximately horizontal direction of the conductor crimp section 51 in a crimp state and a crimp height H1 which is a length in an approximately vertical direction of the conductor crimp section 51 in a crimp state are limited by, for example, a size and a shape of a cavity formed in a connector on which the crimp terminal is mounted, a shape of a crimp tool, a mechanical strength between the conductor crimp section 51 and the conductor 60.
Accordingly, although the shape of an outer surface of the conductor crimp section 51 in a crimp state is restricted in a width-direction cross section, the conductor crimp section 51 is plastically deformed without receiving any restriction with respect to the shape of an inner surface and a wall thickness of the conductor crimp section 51. As a result, in the conventional crimp-connection structural body, as shown in FIG. 15, there has been a case where a gap or the like is formed between an inner peripheral surface of the projecting portion 53 and an outer peripheral surface of the conductor 60.
That is, provided that the crimp recessed portion 52 has an arbitrary shape, the shape of an inner surface and the wall thickness of the projecting portion 53 cannot be controlled. Accordingly, the crimp-connection structural body has a drawback that a contact length of a contact portion between an inner peripheral surface of the conductor crimp section 51 and an outer peripheral surface of the conductor 60 becomes unstable.